You may install, use, access, display and run one copy of the Product on a single computer, such as a workstation, terminal or other device (“Workstation Computer”). The Product may not be used by more than two (2) processors at any one time on any single Workstation Computer.

First of all, for me 'two processors' at one time means, two physical processors (not one processor with multiple cores), secondly, you are using it on the same 'single' computer, and at any one given time, only one 'instance' of the OS can be used by you, hence as long as you stay within these limits I think it would be ok.

Archean makes an interpretation of MS 'rules' that seems fine to me. If you would care to explain 'why' you want two copies, I think you will still have every support - for instance, an extremely tightly 'locked down' copy for your children, plus a more 'capable' version for yourself would be a perfectly sensible thing to do.

On the other hand, there might be another reason, for which we might suggest a different and better way of doing the same thing, such as using MS virtual PC or Sun's virtualbox, or vmware. These alternatives have extra advantages, such as being permanently available without having to reboot, or run simiultaneously, and also being able to be backed up and restored again in exactly the same original condition in moments. I mention these because you may not be aware of them.

Let me explain. You may install, use, access, display and run one copy of the Product on a single computer, such as a workstation, terminal or other device (“Workstation Computer”). You may install one XP copy without buying another one. If you're not sure what they mean, ask them.